ERPNext

ERPNext is an open-source ERP that brings accounting, stock and inventory, manufacturing, CRM, projects, and human resources into a single workflow, with a helpdesk and point-of-sale included. Every transaction is recorded in a double-entry ledger, and the web interface exposes the same records to accountants, store managers, and recruiters alike.

Small and mid-sized companies run their operations on it, often replacing a mix of spreadsheets and licensed ERP modules.

Self-hosting it means financial and staff data never leaves your servers, with no per-user licence cost and a database that backs up like any other.